This invention relates to iontophoretic devices. More particularly, this invention relates to iontophoretic devices that use electric current to drive ionic species, such as fluoride ions, into hard or soft tissue, including teeth to relieve dentin sensitivity.
According to at least one estimate, as many as 40 million Americans suffer from dentin sensitivity (Cooley, R. L. xe2x80x9cEffectiveness of potassium oxilate treatment on dentin hypersensitivity,xe2x80x9d Gen Dent. at 330-333 (July-August 1989)). Moreover, the incidence of hypersensitive dentin is much higher among patients with dentin surfaces exposed by cervical erosion, gingival recession, hypoplasia, or periodontal surgery (Gendusa, N. J. xe2x80x9cSpecial Report, An Introduction To Fluoride Iontophoresis, How To Relieve Dentin Hypersensitivity In Seconds,xe2x80x9d Parkell Today (November 1999)).
According to Brannstron, dentin hypersensitivity may result when fluid movement in open tubules hydraulically stimulates the odontoblasts and nerve fibers at the dentin-pulp junction (Brannstron M, et al., xe2x80x9cThe Hydrodynamics Of The Dentinal Tubule And of Pulp Fluid, Caries Res, 1:310 (1967)).
Gendusa explains that fluoride iontophoresis therapy is known to provide relief from dentin hypersensitivity by driving ionic species into tissue with an electric current. Fendusa also explains that the therapy is based on the principle that similar electric charges repel each other. When sodium fluoride dissolves in an aqueous solution, negatively charged fluoride ions are formed. When a DC circuit is established in a patient""s mouth in the presence of such a fluoride solution, such that a cathode is placed in electrical contact with the hypersensitive tissue, the cathode will electrically repel the fluoride ions into the tooth surface. According to Souder, the fluoride ions react with the calcium in the hydroxyapatite of the dentin to form fluorapatite (CaF2), which is believed to block the tubules with an insoluble compound (Souder W, et al., xe2x80x9cExperimental Remineralization Of Dentin,xe2x80x9d J. Am. Dent. Assoc. 31:1579 (1944)).
A number of chair-side fluoride iontophoresis delivery systems are known, including one sold under model No. D643D, available from Parkell, Electronics Division, of Farmingdale, N.Y. The system includes: (1) a battery-operated dentist-held device, (2) a patient-held grounding device, and (3) an electrically conductive cord connecting the two devices.
The dentist-held device includes a cathodic probe, which is metal, through which electric current can be applied to a patient""s tooth. Before being operated, however, the metal probe is inserted with a cotton pledget into a disposable plastic tube. During operation, an aqueous sodium fluoride solution is applied to the cotton permitting electric current to flow inside the plastic tube from the metal probe to the tooth.
Although the plastic tube and the cotton pledget are disposable, the metal probe is not, which means that it must be sterilized between patients. Such cleaning is costly, time consuming, and introduces a risk of infection if the probe is not properly sterilized.
Iontophoretic toothbrushes are also known, but they are relatively inefficient. The problem is that during normal brushing, the entire mouth is wet by a mixture of toothpaste, water, and saliva. This wet condition normally causes a substantial portion of the electrical current to be directed away from the intended treatment area because the electric current flows along the path of least resistance. Moreover, the magnitude of the electric current applied during an iontophoresis treatment can be limited to the degree of dentin sensitivity.
It would therefore be desirable to provide an iontophoretic toothbrush that efficiently directs electric current toward an intended area, even when the mouth is wet.
It would also be desirable to provide an iontophoresis device that does not require sterilization between patients.
It would further be desirable to provide an iontophoresis device that reduces the amount of time required for an iontophoretic treatment.
It would be still more desirable to provide an iontophoresis device that permits relatively large electric currents to be used during an iontophoretic treatment.
It is an object of this invention to provide an iontophoretic toothbrush that efficiently directs electric current toward an intended area, even when the mouth is wet.
It is also an object of this invention to provide an iontophoresis device that does not require sterilization between patients.
It is a further object of this invention to provide an iontophoresis device that reduces the amount of time required for an iontophoretic treatment.
It is a still a further object of this invention to provide an iontophoresis device that permits a patient to withstand larger electric current during an iontophoretic treatment.
In accordance with this invention, there is provided an iontophoretic apparatus that includes a replaceable cartridge. The replaceable cartridge can be mounted to a handle of the iontophoretic apparatus and includes a container containing an iontophoretic solution, and an applicator assembly fixed to the container that is in electrical communication with said solution in the container.
The replaceable nature of the cartridge eliminates the need to sterilize the applicator assembly each time a patient is treated. Thus, the cartridge is preferably disposable, although, as described below, it can be constructed to be refillable. In any case, the applicator assembly is preferably disposable. The cartridge also supplies a sterile iontophoretic solution to the applicator portion of the applicator assembly during operation. Cartridges having solutions of different concentrations can be provided, as desired.
According to another aspect of this invention, an iontophoretic toothbrush is provided. The iontophoretic toothbrush includes a handle, an electric current source, and an applicator assembly. The handle has an outer surface that is electrically conductive. The electric current source preferably supplies a regulated electric current using, for example, a power source (e.g., a battery), a regulator circuit, and a fuse. The applicator assembly is fixed to the handle and includes a tip portion that includes a brush having a plurality of bristles. Each of the bristles includes (1) an electrically conductive core having a first electrical resistance, and (2) a sheath around the core having a second electrical resistance that is greater than the first electrical resistance. Methods for making and using these apparatus are also provided.